Apparatus for and method of forming a tunnel



y 1932- J. 5. MACDONALD APPARATUS FOR AND METHOD OF FORMING A TUNNELFiled Nov. 15, 1928 Patented duly 5, 1932 i meant arsi J9EE MACDONALD,OF LOIIGQISLAND CITY, NEW YORK Application filed. November 15, 15 281""SeriaI'NQJSIBAWJ My invention relates to a method and apparatus forconstructing concrete tunnels and will be understood from the followingdescription read in conjunction with the drawing, in which:

Fig. 1 is a longitudinal section through a preferred embodiment of myinventionemployed in conjunction with a tunnel undergoing construction;7

Fig. 2 corresponds to Fig. 1, except that the shield by which the tunnelis projected is shown as it appears after an advance;

Fig. 3 is a cross section of Figs. 1 and 2 on the plane denoted by II;

Fig. 4- is a rear View of a part of Figs. 1 and 2; and

Fig. 5 is a perspective view Fig. 1.

.iy invention refers to the construction of tunnels composed principallyof concrete. Such tunnels are built up by advancing a shield in the pathof the projected tunnel and casting the concrete tunnel in progressivesections in the path of the shield. In Fig. 1 I have illustrated atunnel of this type. The tunnel is projected by means of the shield 2which consists of an outer sleeve 3, advancing edge or cutting bit a ofannular form, the inner sleeve 5 and support 6 for the shield advancingmeans. The shield advancing means may be of any form but preferablycomprises a series 7 of jacks operated by a fluid sum as air or Water.conveniently be of the piston type comprising cylinders Shaving pistonsinternal thereto rigidly secured to shafts, such as 9, adapted to beprojected by the introduction of a fluid under pressure to the cylindersby means of inlets 10. In Fig. 2 the acks are shown at the terminationof an advance with the shafts 9 in extended position. It will, ofcourse, be understood that the earth'may be cut away in advance of theshield in the conventional manner and that any earth loosened by the bitor cut away in advance of the shield may be continuously or periodicallvremoved by any suitable means. In constructing the tunnel I employ aform hav ing an exterior corresponding to the interior of the projectedtunnel. The outer sleeve of a part of These jacks may of theshield 2-andthe ibite are preferably 'of a diametersubstantially equal tothe-outside diameter of the finished tunnel. :T-he

form-l2 may be of any desired type butpreferably consistsof a number ofarcu'ate sec- 5."-

tions 13 having internally projecting flanges by Which theindividualsections may be oinedto other sections-t0 make up theassembledform. The shield advancingmeans is provided with; feet 314vadapted to bear 60 directly uponthe assembled form 12 sothat the shieldmaybe advanced utilizing the assembled form as an Labutinentythereby.rendering it possibleto expedite the-work and advance the shieldindependentlyo-f the time ti so that the resistanceof the form to longihtudinalslip is suiiicient to permit itto serve as anabutmenft forthispurpose without substantial movement :relative to the tunnel.

After each advance of the shield the shafts .9 and attachedfeet 14 areretracted-and the- Tb form 1 2 is built-up and advanced to a pointadjacentthe-new position-of the shield; 1 may make successive advancesof the shie'ld in this manner independently of the vmethod of placingthe concrete or place concretegini-ei the annular space surnounding theadvanced form12 prior to eachfsucceedmg advance of the shield.- Ipreferably,-however, make number of advances of the shield and aftereach advance extend-the form -to apoint i adjacent the shield toserve-asan abutment for each succeeding advance and after havmg made a number ofadvances of the shield and "extensions of the form in this mannerplace'concret'e inth'e annular space surround-lees ing the extendedform. .I may also, ut1l1-ze the shield advancing means to com-press. theunset concrete. For this purposethefeetle which engage the form'12- areprovided with externally projecting portions 14a 'awhiclnfflimayiengageplanks or plates or any other means for distr buting aload ontothesunset concreteat theadvancing edge of :the tunnel.

By zplacing planks or plates in position with respect tothe feet 14;prior to an advances mm j of the shield these planks or plates areforced against the unset concrete and operate to compress the unsetconcrete and force it into the space left vacant by the advance of theouter sleeve 3 or any other holes, cavities or soft spots which mayexist in the surrounding stratum, and thereby eifectually preventsubsidence of the earth above the tunnel. This also furnishes aneflective means for tamping the concrete and imparting homogeneity andhigh strength thereto. It will, of course, be understood that theprojecting portions 14a may be made so wide as to distribute thecompressive load onto the unset concrete without the use of planks orplates 7 for this purpose. It will also be understood that after eachadvance of the shield, or at any time thereafter, I may remove sectionsof the form remote from the advancing edge and, if desired, may bringthese sections forward and utilize them at the advancing edge to extendthe form 12.

It will be understood that the specific embodiment of my inventionhereinabove described is by way of illustration and not of limitation.It is my intention that the invention be limited only by the appendedclaims in which I have endeavored to claim broadly all inherent novelty.

I claim;

1. The method of constructing a concrete tunnel which comprises forminga tunnel and advancing a shield having a tail portion, successivelyplacing in the tunnel rearwardly of the shield and in contactingrelation to each other sections of a sectional form having the contourof the tunnel and of dimensions to provide a space between the outerwalls of the form and the inner walls of the tunnel and the tail portionof the shield, placing concrete in the said space, advancing the shieldby means which simultaneously engage the forward edge ofthe form and theconcrete and, through the advancing means, applying pressuresimultaneously to the concrete, to the form and to the shield, wherebythe concrete is compressed and forced into the space left by the tail ofthe advancing shield and also into other cavities existing in thesurrounding stratum simultaneously tunnel, whereby pressure may beexerted simultaneously on the shield to advance it, and on the form andon concrete within the said space to compress it and force it intocavities in the tunnel wall.

In testimony whereof, I have signed my name to this specification this2nd day of November, 1928.

JOHN S. MACDONALD.

with the advancing of the sleeve and its tail portion.

' 2. An apparatus for constructing concrete tunnels comprising anadvancing shield, an assembled form consisting of a number or sectionscontacting with each other at their margins, said form being of lesseroutside radial dimensions than the shield so as to leave a space betweenthe walls of the form and the walls of the tunnel to receive concrete,and means bearing against the shield for advancing it and havingabutments to bear against the forward edge of the form, said abutmentshaving ofiset portions overlapping the entire space between the form andthe ice

